A METHOD OF MAKING A PACK FOR FOOD AND THE ASSOCIATED PACK

Abstract

A method of making a pack for food comprising the following steps. Forming a tray by providing a tray laminate comprising a fibrous web (21) bonded to a web of a gas barrier film (20) comprising a multi-layer laminate comprising a heat sealable layer and a gas barrier layer. Vacuum and/or thermoforming the laminate to create a tray with an upstanding rim. Filling the tray with a food product (F). Providing a web of lid film (13), the lid film (13) being a gas barrier film comprising a multi-layer laminate comprising a heat sealable layer and a gas barrier layer. Heat sealing the lid film (13) to the gas barrier film of the tray around the periphery of the tray to create a hermetic seal between the two barrier films. Severing the pack from the webs of material.

Claims

1. A method of making a pack for food, the method comprising the steps of: forming a tray by providing a tray laminate comprising a first fibrous web bonded to a web of a gas barrier film comprising a multi-layer laminate comprising a heat sealable layer and a gas barrier layer; vacuum and/or thermoforming the laminate to create a tray with an upstanding rim; filling the tray with a food product; providing a web of lid film, the lid film being a gas barrier film comprising a multi-layer laminate comprising a heat sealable layer and a gas barrier layer; adhering a second fibrous web having a window to the lid film to form a lid laminate; heat sealing the lid film to the gas barrier film of the tray around the periphery of the tray to create a hermetic seal between the two barrier films; and severing the pack from the webs of material.

2. (canceled)

3. (canceled)

4. A method according to claim 1, wherein the first fibrous web of the tray is at least three times the thickness, preferably at least four times the thickness and more preferably at least five times the thickness of the gas barrier film of the tray.

5. A method according to claim 1, further comprising the step of printing on the first fibrous web of the tray prior to creating the tray laminate.

6. A method according to claim 1, further comprising the step of printing on the second fibrous web prior to creating the lid laminate.

7. A pack for food, the pack comprising a tray thermoformed from a laminate of a fibrous web and a web of a gas barrier film into a tray with an upstanding rim, and a gas barrier film lid heat sealed to the sheet of gas barrier film in the tray around the periphery of the tray to create a hermetically sealed enclosure between the two barrier films.

8. A pack according to claim 7, wherein the lid is a laminate of a second fibrous web and the gas barrier film.

9. A pack according to claim 8, further comprising a window in the second fibrous web.

10. A pack according to claim 7, wherein the fibrous web is printed.

11. A pack according to claim 8, wherein the second fibrous web is printed.

12. A pack according to claim 7, wherein the heat sealable layer is a polyolefin.

13. A pack according to claim 7, wherein the gas barrier film is ethylene vinyl alcohol copolymer (EVOH) or silicon oxide (SiOx).

14. A pack according to claim 7, wherein the heat sealable layer has an anti-mist coating.

15. A method according to claim 1, wherein the heat sealable layer is a polyolefin.

16. A method according to claim 1, wherein the gas barrier film is ethylene vinyl alcohol copolymer (EVOH) or silicon oxide (SiOx).

17. A method according to claim 1, wherein the heat sealable layer has an anti-mist coating.

Description

[0016] An example of a method and pack in accordance with the present invention will now be described with reference to the accompanying drawings, in which:

[0017] FIG. 1 is a schematic drawing showing the manufacturing process and FIG. 2 is a cross-section through an edge of the pack showing the layer structure.

[0018] With reference to FIG. 1, the materials required to create the lidding for the final pack are supplied from two reels, 1, 2 in a lid manufacturing stage L. The reel 1 supplies a web of fibrous lid material 5. This may be, for example, a paper of 70 gsm. Having a thickness of 80 microns. The fibrous lid material 5 may have been pre-printed on its upper surface 6. Alternatively, the fibrous lid material 5 may be printed in-line as part of the lidding production process by a printer 7. The film then passes a cutter 8 which will cut apertures into the web which will become windows in the finished pack P.

[0019] The reel 2 supplies the gas barrier film for the lid. The film is a multi-layer high barrier film, where one side is a polyolefin, such as 12-40 microns of Poly-Ethylene, which will form a heat seal layer. The other surface of the film may be the same, or a different polymer, such as 12-40 microns of PET. In addition, the film will contain typically 1-5 microns of a barrier substance, such as EVOH or SiOx. Additional layers and tie layers may also be present to complete the gas barrier film. The gas barrier lid film 9 may have antimist properties on the internal, heatseal surface or a food grade antimist coating may be applied separately before it passes below an adhesive applicator 11 which applies a film of adhesive to the other side of film 9 before the two webs or material are brought together in a lamination region 12 to create a lid laminate 13. Alternatively, adhesive may be applied to the fibrous lid material 5.

[0020] The materials required to make the tray of the final pack are supplied from two reels, 3, 4 in a tray manufacturing stage T. A gas barrier film 20 is fed from the reel 3 past an adhesive station 21 which applies a film of adhesive to the gas barrier film 20. This film is preferably a PE/EVOH/PE High Barrier film with or without additional layers and a total thickness of typically 35-50 micron but could be any other formable HB film. A web of fibrous tray material 21 is fed from the reel 4. The fibrous tray material is a material of typically 200-400 micron thickness at (150-300 gsm) and may either be pre-printed or printed in line with this process, as described for the lidding material. The adhesive may alternatively be applied to this material. The two materials 20, 21 are laminated at rollers 22 to produce a tray laminate 23.

[0021] The final, sealed, packaging product, is produced on lines at a pack manufacturing stage P. Typically, this is done on a site where the packs are to be assembled and filled which is generally different to the site where the lid laminate 13 and tray laminate 23 are formed. The tray laminate 23 is fed to a thermoforming tool 24 with a male die 25 and female die 26 in the shape of the tray. These apply heat and pressure to the tray laminate 23 in a manner well known in the art to create a recessed tray shape having a depth of typically 15 mm. Alternatively there may only be one die and a combination of air pressure and vacuum may be used to shape the web to the die, with or without the application of heat. Although the schematic drawing shows only one such tray being formed, in practice, there will be an array of male and female dies such that multiple tray shapes will be formed in the web across and along the base laminate 23 simultaneously.

[0022] The tray laminate 23 then passes to a filling station 28 and a conveyor 29 where the recessed tray shapes are filled with a stack of food items F or an individual item. The tray laminate 23 then passes on the conveyor 29 beneath a roller 30 which receives the lid laminate 13. The lid laminate 13 is pressed onto the tray laminate and heat is applied around the rim of each tray using a heat sealing platen to create a continuous heat seal between the two laminates to hermetically seal the lid to the container.

[0023] The combined laminates which have now been filled are then fed by the conveyor 29 to a cutter 32 where the individual packs P are cut from the web.

[0024] The detail of the pack is shown in FIG. 2. This shows the four layer structure comprising the fibrous lid material 5 and the lid film 9 which are joined together by an adhesive 40 as described above to create the lid laminate 13. The fibrous lid material 5 terminates at an edge 41 providing exposed film 42 which provides the window formed by cutters into an inner cavity 43 in which the food is positioned.

[0025] The tray film 20 is adhered to the fibrous tray material 21 by an adhesive 44 as described above to create the tray laminate 23. The recessed shape which is apparent from FIG. 2 is the shape which is formed in the thermoforming process by the thermoforming tool 24.

[0026] At the lip of the tray, there is a region 45 where the films 9, 20 are heat sealed to one another around the full periphery of the tray thereby ensuring that the enclosure 43 is hermetically sealed. This region 45 may extend in certain regions almost to the outer periphery of the rim. However, in at least one region, ideally a corner portion, there is preferably a release region 46 where the films are left unconnected allowing the user to peel apart the film 9, 20 starting from this region.

[0027] The finished product is one which can be made on a continuous basis on a web-based system. Two webs are brought together in a manner which can create a hermetically sealed container with gas barrier properties which requires significantly less plastic than in the prior art. The fibrous layers can be printed with full colour printing directly onto the pack removing the need for a sticker. Also, different and distinctive shapes of windows can readily be created simply by changing the cutter 8. The finished pack can therefore be made to have a striking overall appearance as well as having a pleasant and more natural feel of a fibrous container as opposed to the conventional plastic.